1. Field of the Invention
The present invention relates to an erasable writing ink composition which can be erased with an eraser after writing.
2. Description of the Related Art
As an erasable writing ink composition which can be erased with an eraser after writing, for example, Japanese Patent Application Laid-open No. 59-223769 discloses "a writing ink composition characterized by being obtained by uniformly dispersing a pigment selected from carbon black and aniline black in an aqueous ink containing dissolved polyethylene oxide in the presence of a surface active agent having a polyoxyethylene group". However, with regard to this kind of erasable writing ink composition, erasability itself is not satisfactory, and particularly after a long period of time has elapsed since the writing, erasion is difficult. Various erasable writing ink compositions other than this disclosed composition have been disclosed, but their erasability is still insufficient and a desired effect has not been attained yet.